Study examines nutrient interactions and impact on HLB-affected citrus trees

As UF/IFAS researchers look to extend the life of citrus trees infected with Huanglongbing (HLB), a bacterial disease, there is a consensus that nutrient applications help. Specifically, nitrogen, calcium, and magnesium play a role in boosting the productivity of affected trees. Although, the latter two have been studied much less than nitrogen. New research examines the degree to which those three nutrients aid a tree when varying amounts are used in different combinations.

Eduardo Esteves conducted the research during his master’s degree program in the UF/IFAS soil and water sciences department (SWSD). He worked with Dr. Gabriel Maltais-Landry, assistant professor of sustainable nutrient management systems, and Dr. Davie Kadyampakeni, assistant professor of citrus water and nutrient management, both in SWSD.

“We know these three nutrients are important. However, it’s not clear how they interact to provide the best results in HLB-affected trees,” Esteves explained. “We applied three different amounts of nitrogen in a test plot. Then we split that into plots with different amounts of calcium, magnesium, and both combined.”

Esteves and his colleagues did this for two years on Valencia trees at the UF/IFAS Citrus Research and Education Center. They measured tree size, fruit yield, and juice quality under the different scenarios. The results showed no clear and consistent effect of plant nutrition.


“In our two-year study, we didn’t find a magic formula,” Esteves said. “While one test plot showed tree growth, a different test plot showed positive results in terms of fruit yield. There was no obvious combination of nutrients that positively impacted all the variables we measured.”

The research does show the three different nitrogen applications had no significant effect. That means producers could use less than the IFAS-recommended amount, but only if they optimize other nutrients with a balanced nutritional program. Esteves points out that using less nitrogen in combination with the other nutrients still leads to good productivity. In addition, producers could save money using less nitrogen, which would also benefit the environment.

“Overall, more research is needed on the impact of these nutrients both in terms of duration of the study and test site location, as our study was a two-year study in one location, and we know citrus trees take time to respond to changes in fertilization,” Esteves said.

Funding for this HLB research came from the USDA Multi-Agency Coordination (MAC) Group, which includes the department’s Animal and Plant Health Inspection Service (APHIS), and the UF/IFAS Citrus Initiative. The research was published in the journal HortScience, a journal of the American Society for Horticultural Science. You can see the full article here:

A companion publication on nutrient cycling in soils related to this study is coming soon in the journal Nutrient Cycling in Agroecosystems.


Posted: December 19, 2021

Category: AGRICULTURE, UF/IFAS Research
Tags: Citrus, Davie Kadyampakeni, Eduardo Esteves, Gabriel Maltais-Landry, HLB

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